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<p>[QUOTE="Leadfoot, post: 1335137, member: 2972"]Again, the (primary) reason part of the coin is not in focus is because it is not perfectly parallel to the camera.</p><p><br /></p><p>The reason you don't see it so much in smaller coins is because all things being equal the coin is "off" more in the larger example. </p><p><br /></p><p>The "curve" of the lens has nothing to do with it.</p><p><br /></p><p>There are two easy ways to solve the problem, otherwise you'll continue to battle it.... First you can use a level (a simple bubble level will due) to level your table, then do the same to your camera. Vertically or horizontally both work, depending on your setup. The other way to solve it is to buy a copy stand (that has a fixed base and telescoping camera mount). I suppose a third way would be to "eye" it, but that will not be consistent or repeatable like the two former examples. Lastly, increasing the f-stop (i.e. decreasing aperature) will help, but not solve the problem.</p><p><br /></p><p>Personally I use a tripod and bubble level -- and with some practice you can get even the largest coins perfectly sharp from edge to edge:</p><p><br /></p><p><img src="http://www.pbase.com/miker/image/49821202/original.jpg" class="bbCodeImage wysiwygImage" alt="" unselectable="on" /></p><p><br /></p><p>Hope this helps...Mike</p><p><br /></p><p>p.s. the other factor that causes your photo to be out of focus is the depth of field. Specifically DoF is very "thin" causing any angular difference between the plane of the coin and the plane of the sensor to result in an out of focus subject. Depth of field is dependent on two further factors -- magnification factor (a function of subject distance and lens focal length) and aperture (larger aperture (i.e. lower f number) = thinner focal plane, smaller aperture (i.e. higher f number) = thicker focal plane). You can read more about depth of field here: <a href="http://en.wikipedia.org/wiki/Depth_of_field" target="_blank" class="externalLink ProxyLink" data-proxy-href="http://en.wikipedia.org/wiki/Depth_of_field" rel="nofollow">http://en.wikipedia.org/wiki/Depth_of_field</a> You can also get a good book on coin photography here: <a href="http://www.amazon.com/Numismatic-Photography-2nd-Mark-Goodman/dp/193399004X" target="_blank" class="externalLink ProxyLink" data-proxy-href="http://www.amazon.com/Numismatic-Photography-2nd-Mark-Goodman/dp/193399004X" rel="nofollow">http://www.amazon.com/Numismatic-Photography-2nd-Mark-Goodman/dp/193399004X</a></p><p><br /></p><p>p.p.s. just wait until you try and take a photo of a coin in a slab slightly tilted, and none of the above methods work and you have to go back to your 'eye'. <img src="styles/default/xenforo/clear.png" class="mceSmilieSprite mceSmilie2" alt=";)" unselectable="on" unselectable="on" />[/QUOTE]</p><p><br /></p>
[QUOTE="Leadfoot, post: 1335137, member: 2972"]Again, the (primary) reason part of the coin is not in focus is because it is not perfectly parallel to the camera. The reason you don't see it so much in smaller coins is because all things being equal the coin is "off" more in the larger example. The "curve" of the lens has nothing to do with it. There are two easy ways to solve the problem, otherwise you'll continue to battle it.... First you can use a level (a simple bubble level will due) to level your table, then do the same to your camera. Vertically or horizontally both work, depending on your setup. The other way to solve it is to buy a copy stand (that has a fixed base and telescoping camera mount). I suppose a third way would be to "eye" it, but that will not be consistent or repeatable like the two former examples. Lastly, increasing the f-stop (i.e. decreasing aperature) will help, but not solve the problem. Personally I use a tripod and bubble level -- and with some practice you can get even the largest coins perfectly sharp from edge to edge: [img]http://www.pbase.com/miker/image/49821202/original.jpg[/img] Hope this helps...Mike p.s. the other factor that causes your photo to be out of focus is the depth of field. Specifically DoF is very "thin" causing any angular difference between the plane of the coin and the plane of the sensor to result in an out of focus subject. Depth of field is dependent on two further factors -- magnification factor (a function of subject distance and lens focal length) and aperture (larger aperture (i.e. lower f number) = thinner focal plane, smaller aperture (i.e. higher f number) = thicker focal plane). You can read more about depth of field here: [url]http://en.wikipedia.org/wiki/Depth_of_field[/url] You can also get a good book on coin photography here: [url]http://www.amazon.com/Numismatic-Photography-2nd-Mark-Goodman/dp/193399004X[/url] p.p.s. just wait until you try and take a photo of a coin in a slab slightly tilted, and none of the above methods work and you have to go back to your 'eye'. ;)[/QUOTE]
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